Fuel and engine oil composition and its use

ABSTRACT

A composition is provided that contains a major amount of a hydrocarbon base fluid having a viscosity of up to 600 cST at 40° C. and (b) a minor amount of a micronized methyl cellulose having a particle size distribution on average of less than 30 microns. The compositions reduce and control the friction coefficient and anti-wear film of lubricant.

This present application claims the benefit of U.S. Patent Application No. 61/553,582, filed Oct. 31, 2011, the entire disclosure of which is hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to fuel and engine oil compositions and their use, particularly, in combustion engines.

BACKGROUND OF THE INVENTION

Engine manufactures in developed countries are continuously challenged to improve the fuel economy of vehicles in the market place. The original equipment manufacturers for vehicles are being pressured to meet and exceed the Environmental Protection Agency's Corporate Average Fuel Economy (CAFE) requirements as well to reduce the vehicles fuel consumption, which in turn would reduce the dependency on imported oil. CAFE is the sales weighted average fuel economy, expressed in miles per gallon (mpg), of a manufacturer's fleet of passenger cars or light trucks with a gross vehicle weight rating (GVWR) of 8,500 lbs. or less, manufactured for sale in the United States, for any given model year. Fuel economy is defined as the average mileage traveled by an automobile per gallon of gasoline (or equivalent amount of other fuel) consumed as measured in accordance with the testing and evaluation protocol set forth by the Environmental Protection Agency (EPA).

A vehicle fuel economy improvement can be accomplished in many ways. However, it is believed that one major area is friction. Engine friction can be separated into six areas with each area contributing to a certain amount of frictional losses. The approximate area of contribution to engine friction are: 6.0% valve train, 25% piston, 19% rings, 10% connecting rod bearings, 12.5% main bearings, 27.5% pump loss.

Friction modifier such as isohexyloxyproplyamine isostearate or cyclic saturated carboxylic acid salts of an alkoxylated amine or ether amines, which are reported in U.S. Pat. No. 7,435,272, are currently used as friction modifiers in fuel. However, to meet the requirements of ever demanding fuel economy vehicle, it is desirable to provide fuels and motor oils with more efficient friction modification.

Modern engine lubricating oil is a complex, highly engineered mixture, up to 20 percent of which may be special additives to enhance properties such as viscosity and stability and to reduce sludge formation and engine wear. For years antiwear additives for high-performance oils such as zinc dialkyldithiophosphate (ZDDP) has been used that work by forming a protective Zinc polyphosphate film on engine parts that reduces wear. This film, referred to as a tribofilm or antiwear film, is worn away as engine is operated.

SUMMARY OF THE INVENTION

In accordance with certain of its aspects, in one embodiment of the present invention provides a composition comprising: (a) a major amount of a hydrocarbon base fluid having a viscosity of up to 600 cST at 40° C. and (b) a minor amount of a micronized methyl cellulose having a particle size distribution on average of less than 30 microns.

In another embodiment, the present invention provides a fuel composition comprising (a) a major amount of a mixture of hydrocarbons in the gasoline boiling range and having a viscosity of up to 600 cST at 40° C. and (b). a minor amount of a micronized methyl cellulose having a particle size distribution of less than 30 microns.

In another embodiment, the present invention provides a lubricating oil composition comprising (a) a major amount of mineral and/or synthetic base oil and (b) a minor amount of a micronized methyl cellulose having a particle size distribution of less than 30 microns.

Yet in another embodiment, the present invention provides a method for reducing friction coefficient or wear in antiwear film in an internal combustion engine which comprises burning in said engine a fuel composition described above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1—This figure represent the Mini-Traction Machine (MTM) generated friction coefficient values concerning the Pre blend of the 5W30 GF4 motor oil containing micronized Methyl Cellulose as well as non-micronized Methyl Cellulose at various treat rates.

FIG. 2—This figure represents Mini-Traction Machine (MTM) percent friction coefficient difference at each MTM speed between the Pre blend of the 5W30 GF 4 containing Methyl Cellulose polymer vs. the base 5W30 GF4 motor oil.

FIG. 3—This figure represents the Post friction coefficient of the base 5W30 GF 4 lubricant using the Mini-Traction Machine (MTM) and the non-micronized Methyl Cellulose at various treat rates to determine if the friction coefficient of the base lubricant would be improved.

FIG. 4—This figure represent the Mini-Traction Machine (MTM) friction coefficient percent difference at each MTM speed between the fresh 5W30 GF4 motor oil friction coefficient and the resulting friction coefficient developed by the addition of Post Fresh 5W30 GF4 motor oil containing the micronized methyl cellulose and or the non-micronized methyl cellulose at various treat rates.

FIG. 5—This figure represents the particle count between the commercial Methyl Cellulose and the micronized methylcellulose in toluene.

FIG. 6—This figure represents the moisture pick-up difference between the commercial Methyl Cellulose and the micronized methyl cellulose.

FIG. 7—This figure represents the HFRR wear scar results of methyl cellulose.

DETAILED DESCRIPTION OF THE INVENTION

We have found that a hydrocarbon fluid composition comprising: (a) a major amount of a hydrocarbon base fluid having a viscosity of up to 600 cST at 40° C. and (b) a minor amount of a micronized methyl cellulose having a particle size distribution on average of less than 30 microns provide excellent boundary friction value and improves the response of the antiwear film to the micronized methyl cellulose.

A friction modifier works by absorbing its polar end toward the metal surface allowing the two moving metal surfaces to slide over each other easily. Therefore if a friction modifier is able to emulsify with water, which may come in contact with the fuel, the friction modifier becomes an emulsifier and as a consequence may not be attached to the metal surface. In addition if a friction modifier is capable of emulsifying with water and is formulated into a fuel additive package; the emulsifier which is part of the fuel additive package may need to be increased to compensate for the added emulsibility/loss of the friction modifier because any water which may be dispersed in the fuel could cause engine problems such as stalling, hesitation or complete engine failure. Therefore it would be advantageous to develop a friction modifier which is able to reduce friction but also able to enhance antiwear films but not emulsify water and in fact separate the water from the fuel. We have found that micronized methyl cellulose can provide excellent friction modification and antiwear properties even for used/oxidized motor oil as well as fresh motor oil.

Pre Lubricant as used herein indicates the polymer was added directly to the motor oil and then the MTM instrument was used to measure the friction coefficient; hexane was then used to remove the lubricant off the disk and a Profilometer was used to measure the anti-wear film thickness.

Post Lubricant as used herein indicates the friction coefficient of the motor oil was first measured using a MTM instrument; hexane was then used to remove the lubricant off the disk and a Profilometer was used to measure the anti-wear film. Then motor oil containing the selected polymer was added to the disk and the friction coefficient and anti-wear film thickness was again measured.

Commercial methyl cellulose typically has an average particle size of 100 microns or larger. Methyl cellulose is commercially available from Dow Chemical Company, and Aldrich Chemical. It has been found by micronizing the methyl cellulose to an average particle size less than 30 microns, preferably less than 25 microns, more preferably less than 20 microns, most preferably less than 15 microns, the micronized methyl cellulose provides a reduction in the lubricants friction coefficient and anti-wear film. The term “micronized methyl cellulose” means methyl cellulose that has been treated so that the average particle size less than 30 microns. Typically, the micronized methyl cellulose particle size distribution is between 0.1-30 microns, with preferably having an average particle size in the range of about 0.5 to 25 micron. Suitable methyl cellulose typically have a number average molecular weight of at least 1000, preferably at least 1500, more preferably at least 2000, to at most 200,000, more preferably to at most 150,000.

Micronized methyl cellulose can be prepared by subjecting methyl cellulose to molecular segmentation. A process where polymer aggregates are de-entangled via processing is referred to as “Molecular Segmentation”. Molecular Segmentation is a process which increases the critical entropy energy of the polymer aggregate by intrapenetrating the polymer aggregate matrix and generating/developing a simpler singular Methyl Cellulose polymer. This process generates a smaller particle size without degrading the polymers molecular weight. Molecular Segmentation can be generated in a number of ways such as thermally, vibrationally or chemically to name a few.

Examples of methods that can be used for molecular segmentation include spray drying, microfluidization, sonification, pan coating, air suspension coating, centrifugal extrusion, vibrational nozzle, ionotropic gelation, coacervation, interfacial polycondensation, interfacial crosslinking, in-situ polymerization, electrospinning and matrix polymerization

The particle size distribution is given herein by the Sauter mean diameter. The Sauter mean diameter is a measure of the mean particle size per unit surface area. The Sauter mean diameter (also noted as D₃₂) may be calculated from the surface area (A_(p)) and volume (V_(p)) of a particle, according to the formula:

D ₃₂=6*(V _(p) /A _(p))

An effective amount of micronized methyl cellulose is introduced into the combustion zone of the engine in a variety of ways to reduce the friction between the piston ring and the cylinder wall. As mentioned, a preferred method is to add a minor amount micronized methyl cellulose to the fuel or lubricant. For example, micronized methyl cellulose may be added directly to the motor oil or fuel or blended with one or more carriers and/or one or more additional detergents to form an additive concentrate which may then be added at a later date to the fuel.

Generally, micronized methyl cellulose is added in an amount in a range from about 0.001% by weight, to about 10% by weight, based on the total weight of the hydrocarbon fluid. As used herein, the term “minor amount” for the micronized methyl cellulose means about 10% or less by weight of the weight of the hydrocarbon fluid, or may be about 8% or less by weight, or about 6% or less by weight, or about 4% or less by weight, or more preferably about 1% or less by weight of the total composition or even about 0.5% or less by weight of the total composition. However, the term “minor amount” will contain at least some amount, preferably at least about 0.001% by weight, more preferably at least about 0.01% by weight of the total composition. Suitable hydrocarbon base fluid typically comprise mixtures of saturated hydrocarbons, olefinic hydrocarbons and aromatic hydrocarbons and have a viscosity of up to 600 cST at 40° C.

Fuel Composition

It has been found that a fuel containing (a) a major amount of a mixture of hydrocarbons in the gasoline boiling range and having a viscosity of up to 600 cST at 40° C. and (b). a minor amount of a micronized methyl cellulose having a particle size distribution on average less than 30 microns provides reduced wear scar values.

The fuel compositions of the present invention may in addition to the micronized methyl cellulose contain one or more additional additives such as detergents. When additional additives are utilized, the fuel composition will comprise a mixture of a major amount of hydrocarbons in the gasoline boiling range as described hereinbefore, a minor amount of micronized methyl cellulose as described hereinbefore and a minor amount of one or more additional additives. As noted above, a carrier as described hereinbefore may also be included. As used herein, for the micronized methyl cellulose component the term “minor amount” means about 10% or less by weight of the weight of the total fuel composition, or may be about 8% or less by weight, or about 6% or less by weight, or about 4% or less by weight, or more preferably about 1% or less by weight of the total fuel composition or even about 0.5% or less by weight of the total fuel composition. However, the term “minor amount” will contain at least some amount, preferably at least about 0.001% by weight, more preferably at least about 0.01% by weight of the total fuel composition.

The one or more additional detergents are added directly to the hydrocarbons, blended with one or more carriers, blended with micronized methyl cellulose, or blended with micronized methyl cellulose and one or more carriers before being added to the hydrocarbon. The micronized methyl cellulose can be added at the refinery, at a terminal, at retail, or by the consumer.

For gasoline composition, preferred hydrocarbon base fluid are gasoline mixtures having a saturated hydrocarbon content ranging from about 40% to about 80% by volume, an olefinic hydrocarbon content from 0% to about 30% by volume and an aromatic hydrocarbon content from about 10% to about 60% by volume. Such base fluid can be derived from straight run gasoline, polymer gasoline, natural gasoline, dimer and trimerized olefins, synthetically produced aromatic hydrocarbon mixtures, or from catalytically cracked or thermally cracked petroleum stocks, and mixtures. The hydrocarbon composition and octane level of the base fluid are not critical. The octane level, (R+M)/2, will generally be above about 83 for fuel composition. The United States gasoline specification for the hydrocarbon base fluid (a) in the gasoline composition which is preferred has the following physical properties and can be seen in Table 1.

TABLE I US Gasoline Physical Properties Properties Units Min Max Vapor Pressure psi 6.4 15.0 Distillation (° F./Evap) vol % 10% 122 158 50% 150 250 90% 210 365 EP 230 437 Drivability Index* 1050 1250 *DI = 1.5(T10) + 3.0 (T50) + 2.4 (ETOH vol %)

The gasoline specification D 4814 controls the volatility of gasoline by setting limits for the vapor pressure, distillation, drivability index and the fuels end point.

The European Union gasoline specification for the hydrocarbon base fluid (a) in the gasoline composition in which is preferred has the following physical properties which are shown in Table 2.

TABLE 2 European Gasoline Specification Properties Units Min Max Vapor Pressure Kpa 45.0 90.0 % Evap at Vol %  70° C. 20 50 100° C. 46 71 150° C. 75 FP 210 Distillation Residue 2 VLI (10 VP_(psi) + 7 E70) 1050 1250

Hydrocarbons in the gasoline can be replaced by up to a substantial amount of conventional alcohols or ethers, conventionally known for use in fuels. The base fluids are desirably substantially free of water since water could impede a smooth combustion.

Normally, the hydrocarbon fuel mixtures to which the invention is applied are substantially lead-free, but may contain minor amounts of blending agents such as methanol, ethanol, ethyl tertiary butyl ether, methyl tertiary butyl ether, tert-amyl methyl ether and the like, at from about 0.1% by volume to about 17% by volume of the base fuel, although larger amounts may be utilized. The fuels can also contain conventional additives including antioxidants such as phenolics, e.g., 2,6-di-tertbutylphenol or phenylenediamines, e.g., N,N′-di-sec-butyl-p-phenylenediamine, dyes, metal deactivators, dehazers such as polyester-type ethoxylated alkylphenol-formaldehyde resins. Corrosion inhibitors, such as a polyhydric alcohol ester of a succinic acid derivative having on at least one of its alpha-carbon atoms an unsubstantiated or substituted aliphatic hydrocarbon group having from 20 to 50 carbon atoms, for example, pentaerythritol diester of polyisobutylene-substituted succinic acid, the polyisobutylene group having an average molecular weight of about 950, in an amount from about 1 ppm (parts per million) by weight to about 1000 ppm by weight, may also be present.

The treat rate of the fuel additive packages that may contain one or more additional additives in the final fuel composition is generally in the range of from about 0.007 weight percent to about 0.76 weight percent based on the final fuel composition. The fuel additive package may contain one or more detergents, dehazer, corrosion inhibitor and solvent. In addition a carrier fluidizer may sometimes be added to help in preventing intake valve sticking at low temperature. Therefore a gasoline additive composition may contain any one or more of the following combinations: Detergent, Carrier Fluid, Dehazer, Corrosion Inhibitor, and Solvent. Examples of additives suitable for gasoline fuel are described in U.S. Pat. No. 5,855,629, which disclosure is hereby incorporated by reference.

For Diesel composition, preferred hydrocarbon base fluid are mixtures having a carbon ranging between C₁₀-C₂₀. Diesel fuel produced by a refinery is a blend of various streams. These streams composed of straight-run, FCC light cycle oil, and hydrocracked gas oil. The refiner must blend the available streams to meet all performance, regulatory, economic, and inventory requirements. The refiner really has limited control over the composition of the final diesel blend. The final blend is determined primarily by the composition of the crude oil feed, which is usually selected based on considerations of availability and cost. The diesel composition and cetane level of the base fluid are not critical. The cetane level will generally be above about 40 but could be as low as 30 for fuel composition. The hydrocarbon base fluid (a) for diesel fuel composition must meet either US ASTM 975 or Europe's EN 590 specifications.

The preferred United States Diesel Fuel physical properties for the hydrocarbon base fluid (a) in the diesel composition can be seen in Table 3.

TABLE 3 US Requirements for Diesel Fuel Oils Diesel Property Method Min Max Flash Point, ° F. D 93 100 130 Water and Sediment, vol %, max D2709/D1796 0.05 Distillation ° F. D86 90% ° F. min 540 640 Kin Viscosity, 40° C., cST D445 1.3 5.5 Ash, max % D482 0.01 Sulfur, (ppm, max) D5453 Diesel # 1 15 Diesel # 2 15 wt % D2622 Diesel # 1 0.05 Diesel # 2 0.05 wt % D129 2.0 Diesel # 1 0.5 Diesel # 2 0.5 Diesel # 4 2.0 Copper Strip, max D130 Diesel # 1 #3 Diesel # 2 #3 Diesel # 4 #3 Cetane Number, min D613 Diesel # 1 and 2 40 Diesel # 4 30 Cetane Index D976-80 40 Aromaticity, vol % max D1319 35 Ramsbottom Carbon Residue, max D524 Diesel # 1 0.15 Diesel # 2 0.35 Lubricity 60° C. WSD, microns, max D6079 520 Diesel # 1 Diesel The European preferred Diesel Fuel physical properties for the hydrocarbon base fluid (a) in the diesel composition can be seen in Table 4.

TABLE 4 European Diesel Fuel Specification Specification Test Method Units Limits Cetane Number EN ISO 5165   51 min Cetane Index EN ISO 4264   46 min Density at 15° C. EN ISO 3675, min kg/m³ 820 EN ISO 12185 kg/m³ 845 Polycyclic Aromatization EN 12916 % (m/m) 11 Hydrocarbons Sulfur EN ISO 20846 mg/kg   50 max 20847   10 max 20884 Flash Point EN ISO 2719 ° C.

 55 Carbon Residue (on 10% EN ISO 10370 % (m/m) 0.30 max dist. Residue) Ash Content EN ISO 6245 % (m/m) 0.01 max Water Content EN ISO 12937 mg/kg  200 max Total Contamination EN ISO 12662 mg/kg   24 max Copper Strip Corrosion EN ISO 2160 3 hours at Class 1 50° C. Oxidative Stability EN ISO 12205 g/m³   25 max Lubricity, WSD EN ISO 12156-1 Um  460 max at 60° C. Vis at 40° C. EN ISOO104 cST  2.0 min  4.5 max Distillation EN ISO 3405 (vol recovered) 250° C. % V/V <65 350° C. % V/V   85 min 95% Point ° C.  360 max Fatty Acid Methyl Esters EN 14078 % V/V   5 max (FAME) content

The Diesel fuel compositions of the present invention may also contain one or more additional additives such as detergents. When additional additives are utilized, the fuel composition will comprise a mixture of a major amount of hydrocarbons in the diesel boiling range as described hereinbefore, a minor amount of micronized methyl cellulose as described hereinbefore and a minor amount of one or more additional additives. The treat rate of the fuel additive packages that contains one or more additional additives in the final fuel composition is generally in the range of from about 0.007 weight percent to about 0.76 weight percent based on the final fuel composition. The fuel additive package may contain one or more detergents, dehazer, corrosion inhibitor and solvent.

Therefore a diesel additive composition may contain any one or more of the following combinations: Detergent, Carrier Fluid, Dehazer, Corrosion Inhibitor, Solvent, Anti-oxidant, De-icer lubricity improver, Cold Flow improver, and Cetane improver. Examples of additives suitable for diesel fuel are described in US2007/0187293, which disclosure is hereby incorporated by reference.

Lubricant Oil Composition

The base oil used in the lubricating oil compositions in the present invention may comprise any mineral oil, any synthetic oil or mixtures thereof and have a viscosity of up to 600 cST at 40° C.

Base oils of mineral origin may include those produced by solvent refining or hydro processing.

Mineral oils that may be conveniently used include paraffinic oils or naphthenic oils or normal paraffins, for example, those produced by refining lubricating oil cuts obtained by low-pressure distillation of atmospheric residual oils, which were in turn obtained, by atmospheric distillation of crude oil.

Examples of mineral oils that may conveniently be used include those sold by member companies of the Royal Dutch/Shell Group under the designations “HVI”, “MVIN”, or “HMVIP”.

Specific examples of synthetic oils that may be conveniently used include polyolefin's such as poly-α-olefins, co-oligomers of ethylene and α-olefins and polybutenes, poly(alkylene glycol)s such as poly(ethylene glycol) and poly(propylene glycol), diesters such as di-2-ethylhexyl sebacate and di-2-ethylhexyl adipate, polyol esters such as trimethylolpropane esters and pentaerythritol esters, perfluoroalkyl ethers, silicone oils and polyphenyl ethers. Such synthetic oils may be conveniently used as single oils or as mixed oils.

Base oils of the type manufactured by the hydroisomerization of wax, such as those sold by member companies of the Royal Dutch/Shell Group under the designation “XHVI” (trade mark), may also be used.

The micronized methyl cellulose may be added to the base oil, but may also be added to other additives then added to the base oil or added at the same time as other additives. As used herein, for the micronized methyl cellulose component the term “minor amount” means. about 10% or less by weight of the weight of the total lubricating oil composition, or may be about 8% or less by weight, or about 6% or less by weight, or about 4% or less by weight, or more preferably about 1% or less by weight of the total lubricating oil composition or even about 0.5% or less by weight of the total lubricating oil composition. However, the term “minor amount” will contain at least some amount, preferably at least about 0.001% by weight, more preferably at least about 0.01% by weight of the total lubricating oil composition.

In addition to the micronized methyl cellulose, the lubricant oils may also contain a number of conventional additives in amounts required to provide various functions. These additives include, but are not limited to, ashless dispersants, metal or overbased metal detergent additives, anti-wear additives, viscosity index improvers, antioxidants, rust inhibitors, pour point depressants, friction reducing additives, and the like.

Suitable ashless dispersants may include, but are not limited to, polyalkenyl or borated polyalkenyl succinimide where the alkenyl group is derived from a C₃-C₄ olefin, especially polyisobutenyl having a number average molecular weight of about 5,000 to 7,090. Other well known dispersants include the oil soluble polyol esters of hydrocarbon substituted succinic anhydride, e.g. polyisobutenyl succinic anhydride, and the oil soluble oxazoline and lactone oxazoline dispersants derived from hydrocarbon substituted succinic anhydride and di-substituted amino alcohols. Lubricating oils typically contain about 0.5 to about 5 wt % of ashless dispersant.

Suitable metal detergent additives are known in the art and may include one or more of overbased oil-soluble calcium, magnesium and barium phenates, sulfurized phenates, and sulfonates (especially the sulfonates of C₁₆-C₅₀ alkyl substituted benzene or toluene sulfonic acids which have a total base number of about 80 to 300). These overbased materials may be used as the sole metal detergent additive or in combination with the same additives in the neutral form; but the overall metal detergent additive should have a basicity as represented by the foregoing total base number. Preferably they are present in amounts of from about 3 to 6 wt % with a mixture of overbased magnesium sulfurized phenate and neutral calcium sulfurized phenate (obtained from C₉ or C₁₂ alkyl phenols).

Suitable anti-wear additives include, but are not limited to, oil-soluble zinc dihydrocarbyldithiophosphates with a total of at least 5 carbon atoms and are typically used in amounts of about 1-6% by weight.

Suitable viscosity index improvers, or viscosity modifiers, include, but are not limited to olefin polymers, such as polybutene, hydrogenated polymers and copolymers and terpolymers of styrene with isoprene and/or butadiene, polymers of alkyl acrylates or alkyl methacrylates, copolymers of alkyl methacrylates with N-vinyl pyrrolidone or dimethylaminoalkyl methacrylate, post-grafted polymers of ethylene and propylene with an active monomer such as maleic anhydride which may be further reacted with alcohol or an alkylene polyamine, styrene-maleic anhydride polymers post-reacted with alcohols and amines and the like. These are used as required to provide the viscosity range desired in the finished oil in accordance with known formulating techniques.

Examples of suitable oxidation inhibitors include, but are not limited to hindered phenols, such as 2,6-di-tertiarybutyl-paracresol, amines sulfurized phenols and alkyl phenothiazones. Usually, lubricating oil may contain about 0.01 to 3 wt % of oxidation inhibitor, depending on its effectiveness. For improved oxidation resistance and odor control, it has been observed that up to about 5 wt % of an antioxidant should be included in the aforementioned formula. One suitable example of such, butylated hydroxytoluene (“BHT”), or di-t-butyl-p-cresol, is sold by many supplies including Rhein Chemie and PMX Specialties. Another suitable example is Irganox L-64 from Ciba Geigy Corp.

Rust inhibitors may be employed in very small proportions such as about 0.1 to 1 weight percent with suitable rust inhibitors being exemplified by C₉-C₃₀ aliphatic succinic acids or anhydrides such as dodecenyl succinic anhydride. Antifoam agents are typically included, but not limited to polysiloxane silicone polymers present in amounts of about 0.01 to 1 wt %.

Pour point depressants are used generally in amounts of from about 0.01 to about 10.0 wt %, more typically from about 0.1 to about 1 wt %, for most mineral oil base stocks of lubricating viscosity. Illustrative of pour point depressants which are normally used in lubricating oil compositions include, but are not limited to, polymers and copolymers of n-alkyl methacrylate and n-alkyl acrylates, copolymers of di-n-alkyl fumarate and vinyl acetate, alpha-olefin copolymers, alkylated naphthalenes, copolymers or terpolymers of alpha-olefins and styrene and/or alkyl styrene, styrene dialkyl maleic copolymers and the like.

As discussed in U.S. Pat. No. 6,245,719, which disclosure is incorporated by reference herein, a variety of additives may be used to improve oxidation stability and serviceability of lubricants used in automotive, aviation, and industrial applications. These additives include calcium phenate, magnesium sulfonate and alkenyl succinimide to agglomerate solid impurities, a combination of an ashless dispersant, metallic detergent and the like, an oxidation inhibitor of sulfur-containing phenol derivative or the like, an oxidation inhibitor or the like, or mixtures thereof. Therefore a lubricant composition may contain any one or more of the following combinations

Base Oil, Micronized Methyl Cellulose, Viscosity Modifier, Pour Point Improver, Additives such as Detergent, Dispersant, Anti-oxidant, Anti-wear, Friction Modifier, Anti-foam, Demulsifiers, Emulsifiers, Rust Inhibitors, Corrosion Inhibitors, Seal Compatibility, Tackifier, Antimist, Biocides, and Dye.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of examples herein described in detail. It should be understood, that the detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. The present invention will be illustrated by the following illustrative embodiment, which is provided for illustration only and is not to be construed as limiting the claimed invention in any way.

Illustrative Embodiment Test Methods

Mini-Traction Machine (MTM)

The Mini-Traction Machine (MTM) is a tribology instrument manufactured by PCS Instruments. The test contact is formed between a polished ¾-inch (19.05 mm) diameter ball and a 46 mm diameter disc, each independently driven to produce a sliding/rolling contact. The test specimens are manufactured from AISI 52100 bearing steel. The disc specimen is mounted on a vertical shaft in the small stainless steel test fluid reservoir. The ball is end mounted on a pivoting shaft and is automatically loaded against the disc at the beginning of the test. DC servomotors drive the specimens, and a high sensitivity force transducer measures the traction force applied to the ball specimen. The slide roll ratio (SRR) is defined as the ratio of sliding speed (U_(ball)−U_(disc)) to rolling speed (U_(ball)+U_(disc))/2. Two test profiles were used in the present program; the first was the Thornton Seq VIB profile, details are provided below. In this testing the same MTM disk and ball was used for a ‘campaign’ of test oils with and without friction modifiers. This testing was based on the philosophy that since the same Zetec engine was used to test a wide variety of lubricants, a more realistic laboratory test would use the same test specimens for multiple oils, especially for comparing oils with and without friction modifier top-treats.

TABLE 5 MTM Operating Conditions, Modified Seq VIB Profile MTM PROFILE Seq VIB Ball speeds 5 to 3000 (3000, 2500, 2000, 1500, 1000, 900, 800, (mm{circumflex over ( )}s⁻¹) 700, 600, 500, 400, 300, 200, 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8, 7, 6, 5) Load 20N, 71N Calculated contact  1.25 pressure (Gpa) SS/R Ratio 100% Temperature (° C.) 125 Run-in procedure 6 speed scans at 71N, 125 C. Test procedure 3 Stribeck speed scans averaged at each load (71N & 20N)

Profilometry (Anti-Wear Thickness Measurement)

Stylus profilometry measurements of the antiwear film height across the MTM disk wear tracks were obtained using a Dektak 6 profilometer, with a nominal 1.0 nm step height resolution. A 5 micron diamond stylus tip was used with a nominal 10 micro-Newton tip force. MTM disks were washed with an ASTM trisolvent (heptane/methanol/acetone in equal mixtures) prior to testing. Line-trace profilometry data (ca. 6000 data points) were taken and averaged at three different locations evenly spaced around the antiwear track. A baseline correction was applied to remove surface curvature from the MTM disks. Antiwear film area was measured by integration of the positive area above the baseline. Antiwear film height was measured by taking the average of the highest 10% of the data points across the wear track.

Average Particle Counting

The particle sizes were determined using a laser-based particle counting/sizing system developed by Spectrex Corporation, model PC-2200. This system uses a laser diode operating at 650 nm to achieve particle counting and sizing through the scattering of the resultant light. The light is focused onto a 2 cm segment of the solution, and the photodetector is positioned to measure light scatter in the near-forward direction of the sample over an angle between 4° and 19°. The photodetector is gated to only allow sizing of in-focus particles, as out of focus particles will produce broadened pulses, which can be removed from the analysis. Typical accuracy of a single pass counting/sizing run is +/− 15%, which can be minimized further through successive runs.

Average Particle Size

A Malvern Masterxizer 2000 outfitted with a Sirocco dry powder accessory was used for the determination of average particle size. An adequate amount of sample is placed within the Sirocco accessory, and the material is then fed into the measuring unit (Mastersizer 2000) using an ultrasonics setting of approximately 50% (to provide a reasonable material feed rate). The critical parameter to be adjusted during this measurement is the air pressure. Since water—soluble polymers absorb moisture well, they often agglomerate easily when not dispersed in a solvent. Therefore, air is used to assist in breaking up these agglomerations. The air pressure is titrated to provide the best measurement conditions. To compare micronized polymer with the commercial starting material, the Sauter mean diameter is used and determined in a toluene solution.

Density (ASTM D70)

The density of the solid was measured using a calibrated pyconometer. The pycnometer and sample are weighed, then the remaining volume is filled with helium. The filled pycnometer is brought to ambient temperature (25° C./77° F.), weighed. The density of the sample is calculated from its mass and the mass of helium displaced by the sample in the filled pycnometer.

Relative Humidity

The Aquadyne DVS is a fully automated, gravimetric, dual sample water vapor sorption analyzer. It measures adsorption and description isotherms of water vapor both accurately and sensitively, including sorption kinetics, with minimal operator involvement. The weights of two samples are constantly monitored and recorded as the relative humidity is automatically varied by the blending of dry carrier gas with a saturated gas stream using precision mass flow controllers. The small sample chamber ensures rapid changes in sample atmosphere conditions when the relative humidity is altered during an analysis. The Aquadyne DVS instrument is manufactured by Quantachrome Instruments.

High Frequency Reciprocating Rig

This test method covers the evaluation of the lubricity of Gasoline and Diesel fuels using a high-frequency reciprocating rig (HFRR). A 2-mL test specimen of fuel is placed in the test reservoir of an HFRR and adjusted to either of the temperatures (25 or 60° C.). If diesel was going to be evaluated the temperature would be 60° C.; however if gasoline was going to be evaluated, the temperature would be 25° C.

When the fuel temperature has stabilized, a vibrator arm holding a nonrotating steel ball and loaded with a 200-g mass is lowered until it contacts a test disk completely submerged in the fuel. The ball is caused to rub against the disk with a 1-mmstroke at a frequency of 50 Hz for 75 min. The ball is removed from the vibrator arm and cleaned. The dimensions of the major and minor axes of the wear scar are measured under 1003 magnification and recorded.

The HERR test condition is the following:

Fluid Volume 2 +/− 0.2 ml Stroke Length 1 +/− 0.02 mm Frequency 50 +/− 1 Hz Fluid Temperature 25 +/− 2° C. Relative Humidity >30% Applied Load 200 +/− 1 g Test duration 75 +/− 0.1 min Bath Surface area 6+/− cm²

EXAMPLES

Fuel

The base fuel used in the test was an 82 R+M/2 base fuel for the fuel composition. The base fuel physical properties can be found in Table 6.

TABLE 6 Base Fuel Physical Properties API Gravity 54.5 RVP 5.38 Distillation, (° F.) IBP 106.5 10% 142.8 20% 176.2 30% 192.4 40% 209.5 50% 228.3 60% 250.8 70% 278.8 80% 309.5 90% 343.1 95% 366.6 End Pt. 415.1 % Recovered 97.2 % Residue 1.0 % Loss 1.8 FIA (vol %) Aromatic 28.6 Olefins 9.7 Saturates 61.7 Gum (mg/100 ml) Unwashed 17 MON 79.0 RON 85.0 R + M/2 82.0 Oxygenates None

Micronized Methyl Cellulose Process

Spray Dry Method

Micronized methyl celluloses were prepared using Methocel E4M and A 15LV premium hydroxylpropyl methylcellulose obtained from Dow Chemical Company. The micronized methyl cellulose was prepared using Buchi Model B-290 Spray Drier under the following conditions.

-   -   Solution Preparation: a 3% Methocel/DI water solution is left to         stir overnight.     -   Spray Dyer Settings: Buchi B-290     -   Temperature: 110° C.     -   Aspirator: 100%     -   Air Flow: 600 L/hr     -   Pump Rate: 35%

Once the inlet temperature reaches the set temperature (110° C.), the Methocel/water solution is fed at a 35% pump rate. Once all the solution has been dried, the final product is then collected.

Microfluidization Method

The micronized polymers were prepared using Microfluidics M-110P microfluidizer under the following conditions.

Solution Preparation:

0.1%-3% polymer/DI water/hydrocarbon mixture (55%-99% xylenes)/0.1%-15% (based on total volume) surfactant. (The hydrocarbon preferably has a boiling point greater than 100° C.)

Emulsion Preparation Process

-   -   a. the polymer/DI water and surfactant mixture is processed         through a Ross mixer (or similar) for 3-4 minutes at low speed         (500-4,000 RPM).     -   b. The preprocess mixture is added to a hydrocarbon. The amount         of hydrocarbon is greater than the amount of DI water added. The         resulting solution is once again processed in the Ross mixer for         5-8 minutes at low to moderate speed (1,000-5,000 RPM).     -   c. The resulting polymer/DI water/surfactant and hydrocarbon         emulsion is processed 1 or more times via the microfluidics         equipment to achieve the desired droplet size, this is typically         accomplished in 3 passes.     -   d. The final stage of the process is to dry the final polymer/DI         water/surfactant/hydrocarbon blend in a rotary-evaporator (or         other solvent removal method, such as freeze-drying) to remove         the water and hydrocarbon to produce a very fine powder.         (removal of the hydrocarbon solvent is optional)

The average particle count of the methyl cellulose before and after the micronization process, measured according to the method described above, is provided below.

Commercial Methyl >100 microns (100%) Cellulose: Micronized Methyl Cellulose 5-15 microns (14.8% by wt) 15-30 microns (85.2% by wt)

FIG. 5 shows the micronization process reduces the particle size of the commercial methyl cellulose from over 100 microns to below 30 microns in size in toluene solution by particle counting.

The particle size distribution of the commercial methyl cellulose and micronized methyl cellulose measured according to the method described above expressed as Sauter Mean Diameter (microns) is provided below.

Commercial Methyl Cellulose: 59.4 Micronized Methyl Cellulose 7.5

The density of the methyl cellulose before and after the micronization process measured, according to the method described above, is provided below.

Commercial Methyl Cellulose 1.456 g/cm³ Micronized Methyl Cellulose 1.680 g/cm³

The relative humidity of the methyl cellulose before and after the micronization process measured, according to the method described above, is shown in FIG. 6

FIG. 6 clearly displays the percent moisture results concerning the commercial Methyl Cellulose vs the micronized Methyl Cellulose. As the humidity of the chamber was increased, the micronized Methyl Cellulose was able to absorb a higher percentage of moisture than the commercial Methyl Cellulose. In fact at 95% humidity, the micronized Methyl Cellulose absorbed 51% more moisture than the commercial Methyl Cellulose.

5W30 GF4 Motor Oil

Commercial Pennzoil 5W30 motor oil was used.

TABLE 7 Low Temperature Low Shear Rate Low Shear Rate High shear Rate Low Temperature (° C.) pumping Kinematic Kinematic viscosity (cP) at SAE (° C.) Cranking viscosity, cP max. Viscosity (cST) at Viscosity (cST) at 150° C. and 10⁸ s−1 Grade Viscosity, cP max with no yield stress 100° C. min 100° C. max min 5W30 6600 at −30 60000 at −35 9.3 <12.5 2.9

GF-4 is the energy conserving classification from API. The API GF-4 classification can be obtained from American Petroleum Institute.

Examples 1-8 and 2a-8a FIG. 1 details the friction coefficient of the micronized methyl cellulose polymer at various treat rates with and without encapsulated Ethomeen T12 friction modifier (Examples 1-8). In addition, FIG. 1 includes the non-micronized methyl cellulose polymer for comparison (Example 8). In addition the base fresh 5W30 GF 4 motor oils also shown. Different MTM lubricant metal disks were used for each lubricant tested.

Commercially purchased 5W30 GF 4 lubricant was used for the test. The treat rates and the Ethomeen T12 friction modifier is provided in Table 8 below. The key for below is the following: MMC (Micronized Methyl Cellulose); NPMC (Non-Micronized Methyl Cellulose and ET 12 is Ethomeen T12 form Akzo Nobel Chemical Co.

TABLE 8 No. MM C (wt %) NMM C (wt %) ET12 (wt %) Exp 1 0 0 0 Exp 2 0.5 0 0 Exp 3 1.6 0 0 Exp 4 0.1 0 0 Exp 5 1.15 0 0.45 Exp 6 0 0 0.45 Exp 7 0.05 0 0 Exp 8 0 0.05 0

In FIG. 1, the y axis is the friction coefficient while the x axis is the speed in mm/sec of the MTM disk. In addition the Pre lubricant conditions relates to the following:

-   -   The methyl cellulose polymer was added directly to the fresh         motor oil and then the MTM instrument was used to measure the         friction coefficient; hexane was then used to remove the         lubricant off the disk and a Profilometer was used to measure         the anti-wear film thickness.

FIG. 1 is known as a Stribeck Curve in which you measure the lubricants friction coefficient vs the speed of the rotating disk used in the MTM instrument. The lubricant MTM evaluation was determined at seven different individual MTM speeds, which cover the three regions of lubrication. The speeds and lubricating regions are the following:

MTM Speed Lubricating Regions 3000 mm/sec [Elastohydrodynamic] 2000 mm/sec [Elastohydrodynamic] 1500 mm/sec [Transitional (mixed)] 1000 mm/sec [Transitional (mixed)]  500 mm/sec [Transitional (mixed)]  100 mm/sec [Boundary]  40 mm/sec [Boundary]

It is clear in FIG. 1 the micronized methyl cellulose polymer does have an effect on reducing the friction coefficient of the lubricant. The more methyl cellulose is added to the lubricant, the lower the friction coefficient of the oil. This is especially seen during the MTM speeds (nm/sec) between 40-1200 nm/sec or between boundary and transitional lubricating conditions.

FIG. 2 expresses the data seen in FIG. 1 by subtracting the additized lubricants friction coefficient at the various MTM speeds from the base lubricant (5W30 GF 4) to show the percent frictional difference at the various points along the Stribeck Curve. The base 5W30 GF4 motor oil is represented by the zero line in FIG. 2.

Once again FIG. 2 shows the greatest frictional reduction occurs with the higher dosage of methyl cellulose although even the lower percentage of the micronized methyl cellulose has an effect. Again the maximum friction coefficient reduction takes place during the MTM speeds (nm/sec) between 50-1000 nm/sec.

The treat rates and the Ethomeen T12 friction modifier is provided in Table 9 below. The key for below is the following: MMC (Micronized Methyl Cellulose); NPMC (Non-Micronized Methyl Cellulose and ET 12 is Ethomeen T12.

TABLE 9 No. MM C (wt %) NMM C (wt %) ET12 (wt %) Exp 2a 1.15 0 0.45 Exp 3a 0 0 0.45 Exp 4a 0.05 0 0 Exp 5a 0 0.05 0 Exp 6a 0.5 0 0 Exp 7a 1.6 0 0 Exp 8a 0.1 0 0

Examples 9-15 and 10a-16a

FIG. 3 details the ability of the micronized Methyl Cellulose polymer at various treat rates with and without encapsulated Ethomeen T12 friction modifier to reduce the friction coefficient of the previous lubricant. In addition FIG. 3 includes the non-micronized methyl cellulose polymer for comparison (Example 9). This figure represents the Post friction coefficient of the base 5W30 GF 4 lubricant using the Mini-Traction Machine (MTM) and then rinse the lubricant off the disk with hexane and adding a 5W30 GF4 motor oil containing the micronized Methyl Cellulose and or the non-micronized Methyl Cellulose at various treat rates to determine if the friction coefficient of the base lubricant would be improved. The same MTM lubricant metal disk was used in the evaluation of between the base lubricant and the treated micronized Methyl Cellulose lubricant.

The treat rates and the Ethomeen T12 friction modifier is provided in Table 10 below. The key for below is the following: MMC (Micronized Methyl Cellulose); NPMC (Non-Micronized Methyl Cellulose and ET 12 is Ethomeen T12.

TABLE 10 No. MM C (wt %) NMM C (wt %) ET12 (wt %) Exp 9 0 0 0 Exp 10 1.6 0 0 Exp 11 0 0 0.45 Exp 12 0.1 0 0 Exp 13 1.15 0 0.45 Exp 14 0.5 0 0 Exp 15 0.05 0 0 Exp 16 0 0.05 0

The 5W30 GF 4 lubricant used in FIG. 3 was commercially purchased for this test. In FIG. 3, the y axis is the friction coefficient while the x axis is the speed in mm/sec of the MTM disk. In addition the Post lubricant conditions relates to the following:

-   -   Indicates the friction coefficient of the fresh motor oil was         first measured using a MTM instrument; hexane was then used to         remove the lubricant off the disk and a Profilometer was used to         measure the anti-wear film. Then fresh motor oil containing the         selected polymer was added to the disk and the friction         coefficient and anti-wear film thickness was again measured.

FIG. 3 is known as a Stribeck Curve in which you measure the lubricants friction coefficient vs the speed of the rotating disk used in the MTM instrument. The lubricant MTM evaluation was determined at seven different individual MTM speeds, which cover the three regions of lubrication. The speeds and lubricating regions are the following:

MTM Speed Lubricating Regions 3000 mm/sec [Elastohydrodynamic] 2000 mm [sec [Elastohydrodynamic] 1500 mm/sec [Transitional (mixed)] 1000 mm/sec [Transitional (mixed)] 500 mm/sec [Transitional (mixed)] 100 mm/sec [Boundary] 40 mm/sec [Boundary]

It is clear in FIG. 3 the micronized methyl cellulose polymer does have an effect on reducing the friction coefficient from a previously developed lubricant. The more methyl cellulose used in the lubricant, the lower the friction coefficient. This is especially seen during the MTM speeds (nm/sec) between 40-1200 nm/sec or between boundary and transitional lubricating conditions.

FIG. 4 represent the Post Mini-Traction Machine (MTM) friction coefficient percent difference at each MTM speed between the fresh 5W30 GF4 motor oil friction coefficient and the resulting friction coefficient developed by the addition of 5W30 GF4 motor oil containing the micronized methyl Cellulose and or the non-micronized Methyl Cellulose at various treat rates.

The treat rates and the Ethomeen T12 friction modifier is provided in Table 11 below. The key for below is the following: MMC (Micronized Methyl Cellulose); NPMC (Non-Micronized Methyl Cellulose and ET 12 is Ethomeen T12.

TABLE 11 No. MM C (wt %) NMM C (wt %) ET12 (wt %) Exp 10a 1.15 0 0.45 Exp 11a 0 0 0.45 Exp 12a 0.05 0 0 Exp 13a 0 0.05 0 Exp 14a 0.5 0 0 Exp 15a 1.6 0 0 Exp 16a 0.1 0 0

FIG. 4 expresses the data seen in FIG. 3 by subtracting the additized lubricants friction coefficient at the various MTM speeds from the base lubricant (5W30 GF 4) to show the percent frictional difference at the various points along the Stribeck Curve. The base 5 W30 GF 4 motor oil is represented by the zero line in FIG. 4.

Once again FIG. 4 shows the greatest frictional reduction occurs with higher dosage of the micronized Methyl Cellulose although even the lower percentage of the micronized Methyl Cellulose has an effect. The maximum friction coefficient reduction takes place during the MTM speeds (mm/sec) between 50-4000 mm/sec for the higher micronized Methyl Cellulose treat rates between 0.5-1.6 wt %. In addition, the Ethomeen T12 did reduce the friction coefficient of the lubricant during the MTM speeds (mm/sec) between 50-4000 mm/sec; however the higher micronized Methyl Cellulose polymer reduction was greater.

Example 17-21

FIG. 7 represent the High Frequency Reciprocating Rig (HFRR) Test concerning the wear protection of the micronized Methyl Cellulose polymer and the Non-micronized Methyl Cellulose polymer vs base fuel. The base fuel used during this test is the same fuel found in Table 6. The HFRR test is conducted to determine the wear protection an additive may generate concerning the base fuel.

The treat rates for the Micronized and Non-Micronized Methyl Cellulose is provided in Table 12 below. The key for below is the following: MMC (Micronized Methyl Cellulose); NPMC (Non-Micronized Methyl Cellulose).

TABLE 12 No. MM C (wt %) NMM C (wt %) Exp 17 0 0 Exp 18 0.1 0 Exp 19 0.5 0 Exp 20 0 0.1 Exp 21 0 0.5

The High Frequency Reciprocating Rig results of the fuel treated with Micronized and non-Micronized Methyl Cellulose can be seen in FIG. 7. It is clearly seen the Micronization process allows low wear scar results than the non-Micronization process. The lower the wear scar value the better the additive is protecting the metal surface. FIG. 7 shows the micronized methyl cellulose is better in reducing wear scar values than the non-micronized methyl cellulose. In other words the lower wear scar value of the micronized methyl cellulose is better than the base fuel results while the higher wear scar of the non-micronized methyl cellulose which is higher than the base fuel actually increased the wear scar of the fuel. Therefore the lower wear scar of the micronized methyl cellulose is better for the fuel than non-micronized methyl cellulose. 

What is claimed is:
 1. A composition comprising: (a) a major amount of a hydrocarbon base fluid having a viscosity of up to 600 cST at 40° C. and (b) a minor amount of a micronized methyl cellulose having a particle size distribution on average of less than 30 microns.
 2. The composition of claim 1 wherein the amount of micronized methyl cellulose is in the range of from about 0.001 wt % to about 10 wt %. based on the composition.
 3. The composition of claim 2 wherein the micronized methyl cellulose has a particle size distribution on average of 25 microns or less.
 4. The composition of claim 2 wherein the micronized methyl cellulose is present in an amount in the range of from about 0.01wt % to about 1 wt % based on the composition.
 5. A fuel composition comprising (a) a major amount of a hydrocarbon base fluid having a viscosity of up to 600 cST at 40° C. and (b) a minor amount of a micronized methyl cellulose having a particle size distribution on average of less than 30 microns.
 6. The fuel composition of claim 5 wherein the amount of micronized methyl cellulose is in the range of from about 0.001 wt % to about 10 wt % based on the fuel composition.
 7. The fuel composition of claim 6 wherein the micronized methyl cellulose has a particle size distribution on average of 25 microns or less.
 8. The fuel composition of claim 5 wherein the micronized methyl cellulose is present in an amount in the range of from about 0.01 wt % to about 1 wt % based on the composition.
 9. The fuel composition of claim 5 is a gasoline composition further comprising at least one gasoline additive.
 10. The fuel composition of claim 5 is a diesel composition further comprising at least one diesel additive.
 11. A method for reducing friction coefficient in an internal combustion engine, which comprises burning in said engine a fuel composition of claim
 5. 12. A lubricating oil composition comprising (a) a major amount of mineral and/or synthetic base oil having a viscosity of up to 600 cST at 40° C. and (b) a minor amount of a micronized methyl cellulose having a particle size distribution on average of less than 30 microns.
 13. The lubricating oil composition of claim 12 wherein the amount of micronized methyl cellulose is in the range of from about 0.001 wt % to about 10 wt %. based on the lubricating oil composition.
 14. The lubricating oil composition of claim 12 wherein the micronized methyl cellulose has a particle size distribution on average of 25 microns or less.
 15. The lubricating oil composition of claim 12 wherein the micronized methyl cellulose is present in an amount in the range of from about 0.01 wt % to about 1 wt % based on the lubricating oil composition.
 16. The lubricating oil composition of claim 12 further comprising at least one lubricant additive. 